Chain-conveyor parallel row machines having parallel rows of molds and rotary table machines having concentric groups of molds for making ice confections are known in the art. A chain-conveyor parallel row machine has molds arranged in parallel rows which are caused to linearly advance through a freezing tank by means of a conveying chain. An example of such a machine is shown in U.S. Pat. No. 4,759,197. A rotary table molding machine having concentric groups of molds for making ice confections uses concentric groups of molds in annular sections which are caused to rotatably advance through a freezing tank by means of a circular mold table.
These known types of machines permit certain types of diversified products to be obtained during a work cycle. Multiple-flavored ice confections can be produced as layers of different flavored ices which are obtained by filling molds in successive steps with different products, as the molds advance in a production cycle. Such machines are also capable of producing "shell and core" confections in which the "core" is removed by suction before it solidifies but after the "shell" solidifies. Another product is then introduced into the resulting space within the shell.
U.S. Pat. No. 4,986,080 ("the '080 patent") discloses a chain-conveyor parallel row machine having parallel rows of molds and a method of producing double-flavor ices. The '080 patent is a particular adaptation of the machine disclosed in U.S. Pat. No. 4,759,197. The '080 patent discloses a machine in which parallel rows of molds are intermittently advanced through a freezing section by means of a conveying chain. The parallel rows of molds differ in shape, one row to the next, such that the cross-sections of molds of some rows are stated to be "inscribable" into the cross-sections of molds in other rows. The '080 patent includes metering-filling units, a stick-inserting unit and withdrawing devices such as are known in the art.
In general, chain-conveyor parallel row machines have certain operational disadvantages. These include: inefficient mold utilization, resulting from fewer than 50% of all molds being in use at any time; inefficient floor plan utilization, resulting from the complete machine having a significant length; poor repeatability of mold positioning, resulting from variations in conveyor chain pitch dimensions due to wear; and incomplete sealing of the mold area from the freezing area, resulting from jointed, articulated construction inherent in a chain conveyor.
Rotary machines resolve several of these difficulties. Molds are located in a circular unitized mold table that effectively seals the product from the mold chilling brine, which is a hygienic advantage. The chain-conveyor parallel row machines carry molds in a jointed, articulating conveyor that is difficult to seal in order to avoid product contamination by the mold chilling brine. Also, unlike the rotary table machine, the chain-conveyor parallel row machine requires that molds be returned to the "start" position by passing molds upside down under the machine typically through an energy and water consuming washing system. The manner of returning molds to the start position results in a mold utilization factor of less than 50% whereas a mold utilization factor for rotary table machines can be higher than 75%. Mold utilization factor is important because molds are expensive.